The importance of proper running and riding lights on vessels using public navigable waters cannot be over emphasized. During the hours of darkness, it is the function of these lights in clear weather to give such timely and effective notice to one vessel of the proximity of another that all doubt as to her character and intentions will be satisfactorily settled before there is any serious risk of collision. Even in thick fog, with the mariners' safety in an approaching situation dependent upon sound rather than upon sight, it is often the glimmer of these same lights through the haze that finally enables each fog enshrouded vessel safely to feel her way past the other. The definitions for proper lights are set forth in the Final Act of the International Conference on Revision of the International Regulations for Preventing Collisions at Sea, 1972, (72 COLREGS), the International Rules of Navigation Act of 1977 (33 U.S.C. 1601), and the Inland Rules. It is significant that 16 of the 38 International Rules and 16 of the 32 Inland Rules relate wholely or in part to lights. In cases of collision, the courts are as certain to hold a vessel at fault for improper lights as for a violation of signal requirements or for failure to maintain a proper lookout.
it is evident from the case law that mere volume of light, even for a vessel at anchor on a clear night, does not constitute the due notice to which approaching vessels are entitled or satisfy the requirement for regulation of lights.
The importance of having lights conform to the specific regulations has been brought out in a number of cases in which incorrect lights, though visible, proved misleading to approaching vessels. Strict compliance with the regulations is thus required.
By way of example, the regulations for starboard side lights as set forth in Article 2, International Rules, read as follows:
"On the starboard side a green light so constructed as to show an unbroken light over an arc of the horizon of 1121/2 degrees (10 points of compass) so fixed as to throw the light from right ahead to 221/2 degrees (2 points) abaft the beam on the starboard side, and of such a character as to be visible at a distance of at least 2 miles."
The regulations for side and stern lights promulgated in the '72 COLREGS are in much greater detail and are defined in Rules 20 through 31, inclusive, and in Annex 1, paragraphs 2 through 5 and 7 through 13.
Heretofore all known navigational lights required to have horizontal arcs of visibility of less than 360.degree., as above set forth for side lights, achieved these arcs by the use of screens or equivalent opaque obstructions which blocked the light from the sectors outside of the desired arcs of visibility. The sharpness of the limiting boundaries were a function of the size of the light source, the distance from the source to the screen, and the length of the screen. Since the light source has finite size, achievement of a sharp cutoff is not possible. Very long screens, on the order of several feet, are satisfactory for meeting legal definitions of "proper lights," but are not suitable for small vessels. On small vessels, screens, if they are used at all, are too short to be effective. Consequently, small vessel lights have traditionally had only vaguely defined arcs and ranges of visibility.
The 1972 International Regulations, 72 COLREGS, have now established precise requirements for navigation lights with respect to (a) range of visibility, (b) arcs of visibility and (c) chromaticity. The net result is a very difficult design requirement for small vessel lights.
The U.S. boating industry has vigorously opposed ratification of the 72 COLREGS on the basis that compliance by small boats is technically and economically infeasible. Nevertheless, Congress passed the International Rules of Navigation Act of 1977 (33 U.S.C. 1601) which, among other things, provides civil penalties against operators of vessels not in compliance with the 72 COLREGS. In compliance with the Act, the United States Coast Guard has promulgated proposed rules for navigation lights for vessels under 20 meters in length (Federal Register, Sept. 7, 1978), which provide for testing and certification of navigation lights, and require the lights installed after Aug. 1, 1981 have USCG certification.
Several foreign manufacturers have produced lights which purport to meet the 72 COLREGS. These lights use high intensity point or line filaments, are rather large, and are expensive, both in initial cost and cost of operation. In these lights, the typical lamp consumes 25 watts (2 amperes per lamp in a 12 volt system). As a consequence, the burning of port, starboard and stern lights for 12 hours will draw 72 ampere hours from the vessel battery. This is an intolerable battery drain for a sailboat and would typically require two hours of engine time per day to restore the battery.
The increase in wattage is due to the requirement for increased visibility. High power is needed because the point or line source and screen geometry provide no optical gain. In an effort to achieve relatively small cutoff angles of visibility, only the light radiating directly from the filament is used, giving an optical gain of unity. Also, high power is required due to the chromaticity specifications which require more narrow band pass regions in the filters for colored lights. Also, due to the power requirements, lamp service life is rather short, and lamp replacement costs are high.
Despite the efforts put into the design of these new lights, and the expense thereof, the improved lights still do not fully comply with the 72 COLREGS because of the difficulty in mounting and/or maintaining the vertical ligh filament in a precise location relative to the vessel and because the light source, no matter how slim, has finite size and thus (like other prior art running lights) an inherent visibility cutoff angle of several degrees which prohibits attainment of the precise angles of visibility required by the COLREGS.
It is for these reasons, among others, that the boating industry has stated that it is technically and economically impossible for small vessels to comply with the new regulations.